Method of treating metals and treating agent therefor



changed.

20 which is novel erse,

45 thereof:

Patented Sept. 29, 1931 UN'ITEDCSTATE'S- PATENT: mw

mm: .1. w'ILson, or AL'IURAS, mm ALAN s. swans, or Los (museum-0mm; s vsun wnson ASBIGNOB .'IO sun EVANS am rnon or nm'rmo mus AND TREATINGAGENT Trrmron;

K0 Drawing.

This invention relates to amethod of treating metals whereby'theductility hardness, toughness, tensile strength an physical durabilitythereof are increased and/0r The invention particularly relates to amethod of treatment whereby metals of various kinds may be rendered morestrong and tough. The invention also relates to a new and novel treatingagent whereb desirable characteristics may be develope in variousmetals.

It has been well known that metals such as iron and steel may be surfacehardened by the treatment thereof in the presence of charcoal, bone.ash, leather scraps, etc., and that various desirable. characteristicsof metals .may be developed by annealing processes. This. inventiondifierentiates from the prior art, not only by employing a treatingagent, but in addition by the employment 0 steps which have not beenused heretofore in developing desirable characteristics in metal.

By the term metals, as used herein, reference is made to both ferrousand non-ferrous.

-metals, such as, for example, iron, wrought iron, steel, copper, gunmetal, aluminum and the-like. The term also includes various alloys,both ferrous and non-ferrous, such as,

for example, nickel steel, chromium steel, etc.

An object of this invention is to disclose and provide a process wherebythe tensile strength of metals may be materiallyincreased. Anotherobject is to disclose and as provide a process whereby metals may berendered tougher and of greater resistance to rupture.

Another object of this invention is to pro vide a novel treating agentwhereby metal 4e may be rendered stronger and harder. Other objects andadvantages of this invention will be apparent to those skilled in theart from the following detailed description of its preferred mode ofoperation and modification greatly improved. Andesitahereinabovere,

Application fi led December 17, 1928. Serial No. 826,897.

ferred to, isapparently an igneous rock hav- 2 ing a very high meltingpoint and consistin of an aluminum silicate. For purposes 0illustration, a complete analysls of andesite from a deposit in ModocCounty, California, is given herein: Percent Silica (S10 42.70 Ironoxide (Fe O 9.3 Alumina (A1 0,) 30.60 Lime (CaO 10.71 Magnesia( g0) 2.53Manganese dioxide (MnO 0.30 Chromium oxide (Cr- 0 0.04: Phosphorouspentoxide (P 0 0.23 Potassiumoxide K 0 0.06 Sodium oxide e 0; 0.12Sulfur trioxide (SO 0.42 Loss on ignition 2.83

It is to be understood that the above analysis is merely representativeof the general composition of andesite and any mineral of similarcomposition, or coming within]- the I characteristics of andesite, isembraced by this invention. 1

Andesite, found in Modoc County, California, is a greyish white rock ofgreat hardness and is commonly known in the locality as white metal.This material is preferably .comminuted or disintegrated to a state offine division in, order to make it adaptable as a treating agent formetal. The disintegrated 0r comminuted andesite may be used alone,

as a treating agent, or it may be mixed with sand, charcoal, or othersubstantially inert operation is as follows:

The metal to be treated is reduced to a molten condition and thedisintegrated andesite then added to the molten metal. The temperatureof the metal at this stage will, of course, depend upon the meltingpoint thereof. The treating agent apparently does not as the fusingpoint of andesite is above 3000. F.

dissolve to any appreciable extent in metals,

As a result, the treatin agent floats on the surface of the metal an apears to form a sintered mass, or slag like bo y. From about one-fourthof one percent to about fifteen percent of andesite by weight of metalbein treated. is preferably added. The time o contacting may va from aminute or two to several minutes, or example, from two to thirtyminutes. The time of contactingdepends somewhat upon the results whlchit is desired to obtain and upon the quantity of andesite used. Thesmaller the quantity of andesite the longer the time of contactingnecessary in order to produce a given result.

The molten metal may-then be poured into molds and the treating agentskimmed off the top or allowed to remain in the ladle. The molds may becooled in a normal manner, or they may be buried or allowed to cool in apit. The cooling, quenching or annealing, after the metal has been incontact with andesite, does not have to be changed from the method ofcooling, quenching or annealing customarily carried out when thehereinabove treating agent is not used.

It will be found that as a result of this treatment, the metal is verymuch harder and of much greater tensile strength and has a muchhigher-yield point. For example, electrolytic copper was melted byheating to a temperature of about 2200 F., five percent of andesiteadded thereto, the mixture maintained in contact for about fifteenminutes and the metal poured at-about 2000 F. into molds. The cast metalwas maintained in the molds for about fifteen minutes and the caste ingsthen cooled in air. The ultimate tensile strength in pounds per squareinch was increased from 16,360 pounds to 25,967 pounds. The hardness, asdetermined by the Shore scleroscope was increased forty percent.

The elongation of the test pieces during test was increased from 12.5%to 23%, or a relative increase of about 80%. Furthermore, the treatedcopper was not so brittle as the untreated. It is to be understood thatin order to produce solid copper castings it may be necessary to employdeoxidizing materials so as to remove the gases which may be occluded inthe casting. Zinc is very often added to copper castings made in sandmoulds, and if zinc in metallic form is used, about three percent, byweight, may be re quired. If the zinc is added as an alloy with copper,such as a yellow brass or a fifty-fifty copper-zinc alloy, then anaddition of one percent zinc in this form may result in sound castings,but this will depend to a large extent upon the care with whichoxidization is prevented during the melting period.

As another example of the hereinabove described method, pig iron washeated to 2800 F. and about 10% of andesite by The castin air.

weight thereof added thereto while the metal was in molten condition.The metal was allowed to remain in contact with andesite for about threeminutes and poured into molds at a temperature of about 2500 F. wereallowed to cool the molds for a. ut fifteen minutes and t en in Testspecimens made from these castings showed that the untreated metal had atensile strength of 25,124 pounds per square inch, while the treatedmetal had a tensile strength of 34,167 pounds. The untreated metal wasvery brittle and castings could be easily broken by a single blow with ahammer. Castings of the treated metal, however, couldnot be broken evenwhen struck with a sledge hammer. It is to be understood that in all ofthe examples given herein, a portion of the metal bein treated wassubjected to the identical conditions of temperature, time, cooling,etc., that the sample being treated was being subjected to, therebypermitting a direct comparison to be made between treated and untreatedmetal. 7

Chemical analysis of the treated and untreated pig iron, from thehereinabove described example, showed substantially no reduction intotal carbon present, although the treated iron contained about 0.1%more graphitic carbon. Furthermore, the treated iron contained only1.45% silicon while the untreated contained 1.59% silicon.

Steel castin s have also been treated in accordance wit the methodhereinabove described and have shown an increase in tensile strengthfrom 62,000 pounds to 65,000 pounds. llhe steel castings were reduced toa molten condition and while at a temperature of 3200 'F. about twopercent in weight of andesite was added to the metal? The time ofcontact between heated metal and the treating agent was only two.minutes, the treated metal being poured at a temperature of 3000 F. intomolds wherein they were cooled for about three hours and then dischargedand cooled in air. There was apparently no increase in the hardness ofthe steel castings, as determined by the sclerosco and there was slightdecrease in elongation. The yield point in pounds per square inchwasincreased from 38,296 pounds to 41,704 pounds.

Instead of reducing the metals to a molten condition and then treatingthem with a treating agent containing andesite We have found that thetensile strength, hardness and toughness of metals can be verymaterially increased by merely heating the metal to above a red heat andthen contacting the heated metal with the treating agent. For example,metallic bodies may be heated to redness, or a temperature above redheat and then covered with the treating agent and allowed to cool,either in contact with said treating gent or the contactin with thetreating agent maintained for a short of time and themetal cooled out 0contact with the treating agents In additionmetallic objects ma beraised. to the proper temperature while in contact with the treatingagent, or they may be raised to a temperature above red'heat, coveredwith the treating agent and then reheated for a period of time dependingupon the results desired.

' 'a period of from two to fifteen minutes.

After these steel bodies were taken out and allowed to cool in air, itwas found that the yield point had been raised from 35,000 pounds to44,000 pounds and the ultimate tensile strength in pounds per squareinch raised from 42,947 pounds to 73,210 pounds. Structural steel barsheated in a furnace to an orange heat. and then covered with powderedandesite showed an increase in ultimate tensile strength of almost fortypercent. The elongation was reduced from 37.5% to 23%. The yield pointwas increased about 35%.. The surface hardness was very materiallyincreased. By treating nickel steel castings in accordance with thismethod the elasticity could be. increased from about 15% to 73%and theultimate tensile strength from 10 to 17%. The yield point could beincreased approximately 80%.

When surface dusting heated bodies of metal in carrying out this processit was found advantageous to reheat the metal while in contact with thetreating agent. For example, when testing steel, the untreated specimensof which had an ultimatetensile strength of 62,000 pounds per squareinch, the treated bars which had not been reheated in contact with theandesite showed an ultimate tensile strength of 7 ,000 pounds per squareinch, whereas simil r bars treated with the same quantity of treatingagent, but reheated after being covered therewith, showed an ultimatetensile strength of- 71,000 pounds per square inch. Our generalconclusions indicate that it is desirable to maintain the metal incontact with the treating agent at as high a temperature as it iseconomical to use.

As a further modification or adaptation of this process of treatingmetals, crushed or pulverized andesite may be used, either alone or withmolding sand, oil, core oil and core binders in making molds into whichmolten metals may be poured to make castings which riod The treating.

may be distinshed bi heir greater surface hardness an strengtFurthermore, all metals treated by any of the above describedmodifications of our process exhibit pronounced rust-resistingproperties.

The reason for the results obtained by treat- -ing metals with thetreating agent'hereinabove described is not known at present, but thereis no uestion but that the tensile strength, har ess and toughness ofmetals is greatly increased by contacting the metal while in a heatedcondition with andesite.

-Numerous changes and modifications may be made in the method employedin contactmg metals while in a heated condition with a treating agentcontaining andesite, and all such changes and modifications as comewithin the scope of the following claims are embraced thereby.

We claim: y 1. In a process of treating metals the steps of heati ametal to above red heat and contactmg t e heated metal in the absence ofcarbonaceous material with a comininuted material containing andesite.2. In a process of treating metal, the steps of heating metal to abovered heat, placing a comminuted materialfree of carbon containmg andesitein contact therewith, and then 'heatin the metal and material in contacttherewlth together. a

3. In a process of treating metals, the steps of heating a metal toabove red heat, then contacting the heated metal with a disintegratedmaterial substantially free of carbonaceous material but containingandesite and then allowing the metal to cool while in said contact.

4. In a process of treating metals, the steps of heating a metal whilein contact with a comminuted material containing andesite in the absenceof carbonaceous material.

5. In a process of treating metals, the steps 3 of reducing a metal tomolten condition, and contactin a comminuted material containingandesite es of carbon therewith.

6. In a process of treating metals, the steps of reducing a metal tomolten condition, adding a preheated comminuted material containingandesite free of carbon thereto and .then removing such comminutedmaterial together with impurities from the metal.

7: In a process of treating metals, the steps of reducing a metal tomolten condition, addcarbonaceous material but containing'andesitethereto.

9. In a process of treating metals, the steps of reducing a metal tomolten condition, adding from one-half to about fifteen percent byweight of a preheated comminuted andesite free of carbon thereto, andthen removing such added andesite together with slag from the moltenmetal. I

Signed at Alturas, California, this 7th day of December, 1928, by FRANKJ. WILSON.

Signed at Los Angeles, California, this 4th day of December, 1928, byALAN S. EVANS.

FRANK J. WILSON. ALAN S. EVANS.

